Tumble chiller

ABSTRACT

A tumble chiller has a rotary drum with a perforated side wall. The drum is enclosed by a cooling jacket through which coolant such as ethylene glycol may be passed. Cooling liquid such as water or brine fills the drum. The drum has scoop-like projections which cause the cooling liquid to flow across the cooling jacket as the drum rotates. The cooling liquid may follow a path around the inner side of the jacket and then follow a path around its outer side. The drum is drivable in rotation by sprocket meshing with a roller chain fast with a flange at the rear end of the drum.

CROSS-REFERENCE TO RELATED APPLICATION

This application relates to GB Application No. 0521388.9 filed Oct. 20, 2005 and published as GB 2419396 on Apr. 26, 2006; and GB Application No. 0521389.7 filed Oct. 20, 2005 and published as GB 2419397 on Apr. 26, 2006, the subject matter of both foregoing applications being incorporated herein by reference.

BACKGROUND

This invention relates to tumble chillers for cooling articles, particularly but not exclusively bagged food products. Industrially cooked food products may be packed in plastics bags immediately after cooking. In preparation for storage or transportation, the bags, which may weigh seven kilograms for example, need to be cooled from a temperature of say 85° C. to 4° C. A tumble chiller is known for this purpose which includes a drum rotatable within a cylindrical casing about an axis inclined to the horizontal. The drum has a perforated circumferential wall so that cooling water supplied to the casing may flow through the drum in which the bags are tumbled during rotation of the drum. A circuit for the cooling water includes a pump, a filter and a heat exchanger in which ethylene glycol may be used to reduce the temperature of the water to slightly above freezing. The drum is supported by a cantilevered drive shaft which extends from the base of the drum through an end wall of the casing and is coupled to a drive motor.

One problem with the known tumble chiller is that the filter may become blocked if it is overloaded following breakage of a bag, so that the circulation of cooling water is prevented and its cooling effect is lost. A similar problem may arise if the heat exchanger malfunctions and causes the water to freeze. A relief valve therefore has to be provided to allow the cooling water to by-pass the heat exchanger. Another problem is that the bearings for the drive shaft are located below the water level in the drum and its casing. In the event that the seals for the bearings become worn, water may seep into the bearings and corrode them.

SUMMARY

As will be described in more detail hereinafter in connection with preferred embodiments of the invention, these problems are overcome by a tumble chiller in which the drum is supported within a casing, preferably of trough-like form, for rotation about an axis which is horizontal or inclined to the horizontal, rotary drive means being provided above the axis of the drum and spaced therefrom. A bath of cooling liquid, such as water, is provided within the casing, the drum being partially immersed in the water bath. The drive means may take the form of a pinion and ring gear mechanism. The pinion may be arranged above the level of the water even though the ring gear is partially immersed in the water. Any corrosion of the ring gear which takes place has no adverse consequences for the chiller of the invention, unlike in the case of the conventional chiller in which corrosion of the drive shaft bearings may result in the chiller having to be shut down. The peripheral wall of the drum is adapted to allow the water to pass through it. A cooling jacket is interposed between the drum and casing and in operation coolant such as ethylene glycol passes through a passage or passages within the jacket. The drum is adapted during rotation to cause the water to flow through a first passageway defined between the drum and the cooling jacket and into a second passageway between the cooling jacket and the casing. The water enters the second passageway on one side of the drum, flows through the second passageway in contact with the cooling jacket and returns into the first passageway on the opposite side of the drum. It will be appreciated that the flow of water takes place in contact with both sides of the cooling jacket with the result that an enhanced cooling effect is obtained. Because the water is not required to flow through narrow pipes to and from a separate heat exchanger and filter there is no risk of blockages occurring in the event that a bag breaks and releases its contents into the water. In the event that a bag breaks during operation and spills its contents, it is a relatively simple matter for the chiller to be flushed through.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of a tumble chiller embodying the invention;

FIG. 2 is a plan view of the chiller;

FIG. 3 is a cross section taken on line III-III in FIG. 4;

FIG. 4 is a longitudinal section taken on line IV-IV in FIG. 2;

FIG. 5 is a cross section through a fragment of the cooling jacket to an enlarged scale;

FIG. 6 is a section taken on the line VI-VI in FIG. 4;

FIG. 7 is a perspective view of the support and drive system for the drum, and

FIG. 8 is a perspective view, partially broken away of the casings and the drum.

DETAILED DESCRIPTION

Referring to the drawings, a tumble chiller has a box-like outer cladding or housing 2 assembled from panels and carried by a support structure or frame. The cladding is provided with a door 4 in its front wall. The door incorporates a chute 6 to allow bags of hot food product to be introduced into the chiller. Following cooling, the door may be opened and the bags removed by hand.

Located within the cladding is a drum 8 which is rotatable about an axis which extends from the front to the rear of the chiller and is inclined downwards towards the rear, relative to the horizontal. The drum is partially immersed in a bath of cooling liquid, conveniently water or brine, and referred to herein as “water” without limitation. The drum has a rear end wall and a perforated side wall 10 so that water may flow into and out of the drum through the perforations. Systems to be described below are provided for circulating the water through the drum and driving the drum in rotation, so that the bags tumble in the water and are cooled from, say, 85° C. to about 4° C.

The support arrangement for the drum consists of two pairs of laterally spaced, rubber-tyred rollers 12 a and 12 b which engage the radially inner sides of annular flanges 14 a and 14 b, respectively, fixed to or integral with the front and rear ends of the drum at its periphery. Only one roller in each pair is shown in FIG. 4, both rollers 12 b being shown in FIG. 7.

The rollers 12 b for supporting the rear end of the drum are mounted on a support plate 16 forming part of a support structure of the chiller in the region of the upper extremity of the drum. It will be noted from FIG. 4 that the axis of the drum is inclined to the horizontal at an angle of substantially 10°, sloping down from its forward end so that the axes of the rollers are similarly inclined. The rollers at the front end of the drum will necessarily be positioned higher than those at the rear end.

Unless prevented, the inclination of the drum leads to a tendency for the drum to slide rearwardly so that its rear wall binds against the faces of the rollers 12 b. To resist this tendency, a pair of laterally spaced rollers 18 are mounted in brackets on the plate 16 to bear against the end wall of the drum, as shown in FIG. 7.

As remarked above, the conventional tumble chiller is supported in a cantilevered fashion on a shaft fast with the centre of its rear end wall. Demounting of the conventional drum for repair necessarily involves extracting the shaft from its bearings and removing the drum from the front of its cladding. With the arrangement shown in the accompanying drawings it is a relatively simple matter to remove the top panel of the cladding, shift one pair of rollers to disengage from their associated flange, and then lift the drum out of its housing. The support plate 16 may be mounted in such a way that it can be displaced for this purpose.

Drive for the drum is provided by a sprocket 20, the bearings of which are mounted in the plate mid-way between the rollers 12 b. The sprocket 20 meshes with a conventional roller chain 22 welded or otherwise secured to the flange 14 b at the rear of the drum, axially inwardly of the track for the rollers 12 b. The use of a sprocket and roller chain system for driving the drum allows of a simple construction with readily available components. The sprocket is driven from an electric motor 24 through a transmission system 25 mounted on the opposite side of the support plate 16, as shown in FIG. 7.

It will be appreciated that at least the bearings of the support and drive arrangements described above are located well above the level of liquid in the drum so that there is no risk of corrosion of the bearings from direct contact with the liquid. Preferably, of course, the sprocket 20 and the rollers 12 a 12 b and 18 are disposed in their entirety above the water level. The roller chain, however, is partially immersed in the water but this carries with it no disadvantages, as compared with the known tumble chillers in which corrosion of bearings can lead to serious problems.

The drum is housed within a trough-like inner casing 28 of U-shaped cross section. The inner casing has a semi-cylindrical lower portion from which planar side walls extend upwards. A trough-like outer casing 26 similarly of U-shaped cross-section encloses the lower part of the casing 28, the arcuate lower portions of both casings being concentric. The casings serve to retain the water bath mentioned above. An inner passageway 44 is formed between the drum and inner casing on the one hand, and an outer passageway 46 is formed between the inner and outer casings, on the other. Water is supplied to the chiller by way of a pipe 61 and the level maintained by an overflow 62. The casing 28 has a series of four slots 30 disposed in a horizontal row in each of its side walls. The two rows of slots are arranged at the same level, slightly below the level of the overflow. A horizontal flange 42 extends inwardly from each of the upper edges of the casing 26 and is welded to the inner casing 28. A series of openings 43 is provided in each of the flanges to allow the space between the two casings to be cleaned, for example by hosing water through them.

The lower part of the inner casing 28 is formed by a cooling jacket 32 within which is provided a semi-annular passage 33 through which a coolant, for example ethylene glycol, may be passed. Coolant is supplied to the upper region of the jacket on one side through an inlet duct 54. The coolant flows through the jacket, following an arcuate path to an outlet duct 56 arranged to permit the escape of coolant from the upper region of the other side of the jacket. The jacket is of the dimpled type, as depicted in FIG. 5, in which the plates making up the inner and outer skins of the jacket are spot-welded together at longitudinal and transverse intervals to form dimples to enhance the cooling effect. A circuit between outlet duct 56 and the inlet duct 54 externally of the chiller includes a pump for circulating the coolant and a heat exchanger for extracting heat from the coolant. An inlet 58 allows steam to be injected into the water within the chiller after operation so as to cause the water to boil and promote cleaning. An outlet 60 allows the chiller to be drained.

The peripheral wall of the drum has projections 40 in the nature of scoops formed on its sides which run along the length of the drum. The drum is also provided with internal paddles 41 to promote agitation of the liquid within it.

In use, water is admitted to the system and finds as its level substantially that of the slots 30. The water fills the drum and the spaces within the outer casing 26. When bags have been placed within the drum, the motor is started and rotates the drum to tumble the bags. Water may flow through the perforations in the drum between the drum interior and its exterior. The scoops 40 cause water in the inner passageway 44 formed between the drum and the inner casing to circulate in the clockwise direction as viewed in FIG. 6 and to pass through the slots 30 into the outer passageway 46 between the cooling jacket and outer casing, as indicated by the arrow A. In the outer passage the water follows a path around the underside of the drum, to re-enter the inner passage through the slots on the opposite side of the drum, as indicated by the arrow B. A continual flow of water therefore takes place through the drum and around both sides of the cooling jacket, thereby enhancing the cooling effect achieved by the coolant, in comparison with what would be the case if only one side of the jacket is utilized. During operation of the chiller, heat is extracted from the bagged food product by the water, and then extracted from the water by the ethylene glycol coolant.

Because the water jacket has a substantial area, embracing over one half of the surface area of the drum, and the inner and outer passageways for the flow of water are substantially co-extensive with the jacket, there is no risk of flow becoming blocked following breakage of a bag or localised freezing. The cooling effect provided by the jacket is capable of maintaining the water at a low temperature consistent with reducing the temperatures of the bags to the desired level. In the event that the water becomes polluted it is a simple matter to drain the chiller, so that no filter is needed. By inclining the axis of rotation of the drum downwards from its forward end to its rearward end, a greater depth of water is found at the rearward end, away from the door and where the bags tend to accumulate.

Modifications may be made to the tumble chiller described above. For example, instead of the drum having a perforated peripheral wall it may be adapted in some other way to be liquid permeable. Although it is preferred for the drum to rotate about an inclined axis, the drum may be arranged to rotate about a horizontal axis. Construction of the chiller of the invention is simplified and rendered less costly by use of a conventional roller chain, but it would be possible to make use of a toothed ring gear as an alternative. Although as illustrated, drive is transmitted to the roller chain through a single sprocket, two or more sprockets may be used for this purpose. Also, although the use of a trough-like casing facilitates removal of the drum and cleaning, the casing could be provided with a cover piece so as to be generally cylindrical in form. It will also be understood that the invention may be put into effect most effectively by incorporating the drive and cooling systems described above in one and the same chiller. Nevertheless, it is of course possible to take advantage of the improved drive system alone by incorporating it in a tumble chiller in which the water is cooled in the conventional way described above using a separate heat exchanger for this purpose. Likewise, advantage may be taken of the improved cooling system alone by incorporating it in a tumble chiller in which the drum is rotated by a drive shaft having sealed bearings located beneath the water level. These and other modifications are intended to fall within the spirit and scope of the invention as set forth in the claims which follow. 

1. A tumble chiller for articles, particularly in the form of bagged food products, including a casing for retaining a bath of cooling liquid, a rotary drum supported within the casing for rotation about an axis which extends from the front to the rear of the chiller, the peripheral wall of the drum being adapted to allow cooling liquid to pass therethrough, a cooling jacket interposed between the drum and casing, the jacket being provided with an internal passage to enable coolant to pass through the jacket, the drum being adapted during rotation to cause cooling liquid to flow through a first passageway between the drum and the cooling jacket and into a second passageway between the cooling jacket and the casing, the cooling liquid entering the second passageway on one side of the drum, flowing through the second passageway in contact with the cooling jacket and returning into the first passageway on the opposite side of the drum.
 2. A chiller as claimed in claim 1, wherein the casing is in the form of a trough.
 3. A chiller as claimed in claim 1, wherein part of the cooling jacket constitutes a trough-like inner casing enclosing the drum and is provided with openings therethrough on both lateral sides of the drum at substantially the level of cooling liquid during operation, the cooling liquid flowing through the openings between the passageways.
 4. A chiller as claimed in claim 1, wherein the drum is provided with projections in the form of scoops to promote circulation of cooling liquid.
 5. A chiller for articles, particularly in the form of bagged food products, including a support structure, a casing and a drum supported within the casing for rotation about an axis which extends from the front to the rear of the chiller, the casing being adapted to contain a bath of cooling liquid and the peripheral wall of the drum being adapted to allow liquid to pass therethrough, rotary drive and support means being spaced from and above the axis of the drum and the liquid level, the drive means being coupled to rotary driven means associated with the drum and partially immersed in the liquid.
 6. A chiller as claimed in claim 5, further including a drive motor mounted on the support structure, the drum having a forward open end through which the articles are to be introduced, and the drive means for the drum being associated with the rearward end of the drum, the drive means including a pinion which is supported by the support structure and drivable by the motor, the pinion meshing with a driven means comprising a ring gear provided on the rearward end of the drum.
 7. A chiller as claimed in claim 6, wherein an annular flange extends rearwardly from the drum and the ring gear is provided on the flange, and wherein support means for the rearward end of the drum comprises rollers bearing against the flange.
 8. A chiller as claimed in claim 7, wherein the forward end of the drum is supported by rollers.
 9. A chiller as claimed in claim 8, wherein the drum is removable from within the casing by raising the drum vertically following displacement of at least some of said rollers.
 10. A chiller as claimed in claim 9, wherein the ring gear is provided on the radially inner side of the flange, and the rollers bear against said radially inner side.
 11. A chiller as claimed in claim 10, wherein the drive means for the drum comprises a motor and sprocket drivable by the motor, the sprocket engaging with a roller chain extending around and fast with the rearward end of the drum.
 12. A chiller as claimed in claim 11, wherein the chain is mounted on the radially inner side of an annular flange projecting axially from the rearward end of the drum.
 13. A tumble chiller for articles, particularly in the form of bagged food products, including: a) a support structure, b) a trough-like casing for retaining a bath of cooling liquid, c) a rotary drum supported within the casing for rotation about an axis which extends from the front to the rear of the chiller and is downwardly inclined towards the rear, the rearward end of the drum being provided with a reawardly extending annular flange, and the peripheral wall of the drum being adapted to allow cooling liquid to pass therethrough, d) a cooling jacket interposed between the drum and casing, the cooling jacket being provided with a passage to allow coolant to pass through the jacket, the drum being adapted during rotation to cause cooling liquid to flow through a first passageway between the drum and the cooling jacket and into a second passageway between the cooling jacket and the casing, the cooling liquid entering the second passageway on one side of the drum, flowing through the second passageway in contact with the cooling jacket and returning into the first passageway on the opposite side of the drum. e) a drive motor mounted on the support structure, f) a driven means comprising a ring gear provided on the annular flange, g) drive means including a pinion supported by the support structure and drivable in rotation by the motor, the pinion meshing with the ring gear, h) support means for the rearward end of the drum comprising first rollers mounted on the support structure and bearing against the the flange, and second rollers mounted on the support structure and bearing against the end of the drum.
 14. A chiller as claimed in claim 13, wherein the ring gear is constituted by a roller chain mounted on the radially inner side of the flange, and the pinion is constituted by a sprocket, and the first said rollers bear against the radially inner side of the flange.
 15. A chiller as claimed in claim 13, wherein at least part of the cooling jacket constitutes an inner casing enclosing the drum and is provided with a horizontal row of slots on each lateral side of the drum, the slots being located at substantially the liquid level in the drum during operation thereby to enable cooling liquid to flow between the passageways. 